In which of the following alternatives are the three compounds listed in order of increasing boiling point?
(A) Pentane, butan-1-ol, propanoic acid
(B) Propanoic acid, butan-1-ol, pentane
(C) Propanoic acid, pentane, butan-1-ol
(D) Butan-1-ol, propanoic acid, pentane - HSC - SSCE Chemistry - Question 11 - 2008 - Paper 1
Question 11
In which of the following alternatives are the three compounds listed in order of increasing boiling point?
(A) Pentane, butan-1-ol, propanoic acid
(B) Propanoic ac... show full transcript
Worked Solution & Example Answer:In which of the following alternatives are the three compounds listed in order of increasing boiling point?
(A) Pentane, butan-1-ol, propanoic acid
(B) Propanoic acid, butan-1-ol, pentane
(C) Propanoic acid, pentane, butan-1-ol
(D) Butan-1-ol, propanoic acid, pentane - HSC - SSCE Chemistry - Question 11 - 2008 - Paper 1
Step 1
Identify the compounds
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Answer
The compounds mentioned are:
Pentane
Butan-1-ol
Propanoic acid
To compare their boiling points, we need to consider the nature of the compounds and the influences on their boiling points, such as molecular weight and the presence of functional groups.
Step 2
Estimate boiling points
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Answer
Pentane is an alkane with a relatively low boiling point due to weak van der Waals forces. Butan-1-ol, being an alcohol, has hydrogen bonding, which typically raises boiling points. Propanoic acid, a carboxylic acid, also exhibits strong hydrogen bonding but has a higher molecular weight than butan-1-ol, leading to an even higher boiling point.
Step 3
Rank the compounds
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Answer
Based on the above estimations, the order of boiling points is:
Pentane (lowest)
Butan-1-ol
Propanoic acid (highest)
Thus, the correct alternative that lists these compounds in order of increasing boiling point is (A) Pentane, butan-1-ol, propanoic acid.
